JPH01172794A - Object detector - Google Patents

Abstract

PURPOSE:To reduce a sensing range and contrive the improvement in the detecting precision of a minute object by imparting a detector with a directivity without dispersing supersonic waves through a pair of wave guides to propagate. CONSTITUTION:The supersonic waves emitted from a transmitter 3 is propagat ed through a pair of wave guides 1, 2 and received by a receiver 4. Electric signals generated from the receiver 4 are changed depending upon the presence or absence of an object S in the separated space between wave guide 1, 2, thereby detection of the object S can be realized. Since the detector is allowed to have directly to propagate without dispersing the supersonic waves through the wave guides 1, 2, a sensing range of the object S can be reduced in the separating space and the detecting precision of a minute object can be improved. Further, a propagating path of the supersonic waves can be set freely and an installation space of the detector is not restricted by changing a piping configuration such as bending and altering in its length.

Description

DETAILED DESCRIPTION OF THE INVENTION <Industrial Application Field> The present invention relates to an object detection device using an ultrasonic sensor.

<Prior art> Conventionally, in machine tools, etc., as a safety measure in the event that a finger or the like is accidentally inserted into a dangerous place such as a moving part of a tool, a system is used to detect whether the finger or the like has been inserted into a dangerous place. A detection device is used to detect this and to perform an emergency stop of a machine tool or the like.

In addition, in various industrial machines and industrial robots, it is used to detect the completion of movement of a workpiece to a predetermined position, etc.
An object detection device is used.

By the way, such an object detection device conventionally includes a transmitter that generates ultrasonic waves and a receiver that generates an electrical signal by receiving the ultrasonic waves, and detects the ultrasonic waves emitted into the air from the transmitter. Some devices detect the presence or absence of an object between a transmitter and a receiver based on changes in reception on the receiver side.

<Problems to be Solved by the Invention> However, in such conventional object detection devices, the ultrasonic waves emitted from the transmitter diffuse and propagate to the receiver, so the following various problems occur. There was a problem.

That is, as a result of the ultrasonic waves being diffused, the object sensing range is too wide, resulting in poor detection accuracy for minute objects.

Further, due to the diffusion of the ultrasonic waves, if there is an object other than the object to be detected around the installation location, this object will also be detected or the ultrasonic wave will receive reflected waves from the object. Furthermore, there is also the problem that ultrasonic waves cannot reach long distances.

As a result, there are considerable restrictions on the installation location of the object detection device, and the occurrence of the above-mentioned problems is unavoidable due to the peripheral equipment of the machine tool or the like to which it is applied.

Note that in places with a lot of dust, etc., the scattering of the ultrasonic waves due to diffused reflection is significant, and the above problems become more noticeable.

Therefore, in view of the above-mentioned conventional situation, the present invention solves the above-mentioned conventional problems by propagating the ultrasonic waves emitted from a transmitter to a wave receiver with directivity without diffusing them. An object of the present invention is to provide an object detection device that solves the problem.

(Means for Solving the Problems) Therefore, the present invention provides a pair of waveguides that can face each other with their distal ends separated from each other, and a pair of waveguides arranged at the base end of one of the waveguides to emit ultrasonic waves. a wave transmitter that generates an electric signal, and a wave receiver that is installed at the base end of the other waveguide and generates an electric signal by receiving ultrasonic waves, An object detection device is characterized in that it is configured to detect the change in electrical signal generated from a wave receiver.

<Operation> In such a configuration, ultrasonic waves emitted from the wave transmitter propagate through the pair of waveguides and are received by the wave receiver. In this case, the electrical signal generated from the wave receiver changes depending on whether or not an object exists in the space between the waveguides, so the presence or absence of the object is detected based on this.

As a result of giving the ultrasonic wave directivity through the waveguide so that it does not spread and propagates through a limited airspace, the object sensing range can be reduced and the detection accuracy of minute objects can be improved.

In addition, by changing the pipe bending form and length of the pair of waveguides, the propagation path of the ultrasonic waves can be freely set, so the installation location is freer than before without being restricted by the installation space of the device. You can choose. Therefore, it is possible to prevent problems such as detecting objects other than the object to be detected, receiving reflected waves from the objects, and preventing ultrasonic waves from reaching long distances.

<Example> Next, one embodiment of the present invention will be described based on the drawings.

In Figure 1, 1 and 2 are the respective tips (la) (2a)
a pair of waveguides that are spaced apart from each other so that they can face each other; 3 is a transmitter that is installed at the base end of one waveguide 1 and generates ultrasonic waves; 4 is the other waveguide 2; This is a receiver that is installed at the proximal end of the receiver and generates electrical signals by receiving ultrasonic waves. The transmitter 3 and receiver 4 are each provided with an ultrasonic vibrator such as a piezoelectric vibrator, an electrostrictive vibrator, or a magnetostrictive vibrator.

5 is a voltage application circuit for exciting the ultrasonic vibrator of the transmitter 3 to generate ultrasonic waves, and 6 is a detection circuit for detecting the piezoelectric output of the ultrasonic vibrator of the receiver 4.

In this configuration, ultrasonic waves emitted from the wave transmitter 3 propagate through the pair of waveguides 1.2 and are received by the wave receiver 4. The electrical signal generated from the wave receiver 4 changes depending on whether or not the object S is present in the space between the waveguides 1 and 2, and the presence or absence of the object is thereby detected.

According to the object detection device having such a configuration, a pair of waveguides 1.
As a result of allowing the ultrasonic waves to propagate in a directional manner so as not to be diffused through the spacer 2, it is possible to reduce the object sensing range in the separated portion and improve the detection accuracy of minute objects.

In addition, the propagation path of ultrasonic waves can be freely set by bending the pair of waveguides 1.2, changing the piping configuration, and changing the length. First, you can choose the installation location more freely than before, and there is no risk of detecting objects other than the detected object, such as peripheral devices, or receiving reflected waves from such objects, and the ultrasonic waves will not reach far away. It is possible to prevent such problems from occurring.

FIG. 2 shows another embodiment of the present invention, in which a membrane-like vibrating member capable of propagating ultrasonic vibrations to the open end surfaces of the tip portions (1a) and (2a) of a pair of waveguides 1.2 is shown. Membrane rubber 7
It is constructed by pasting.

In this configuration, the ultrasonic waves emitted from the wave transmitter 3 propagate through the air within the waveguide 1 and vibrate the rubber membrane 7. This vibration is further propagated to the rubber film 7 on the end face of the other waveguide 2 through the air outside the waveguide 1, passes through the inside of the waveguide 2, and is received by the wave receiver 4.

As a result of configuring the waveguide 1.2 by pasting the film-like rubber 7 on the end face, the end face can be closed, and water vapor, environmental pollutants, etc. can enter the inside of the waveguide from this end face. It is possible to prevent the propagation of ultrasonic waves from being disturbed by water vapor, environmental pollutants, etc.

In this example, the degree of freedom is t in the waveguide 1.2.
By enclosing various gases and liquids that do not interfere with the ultrasonic waves, it is possible to change the propagation state of ultrasonic waves, and it becomes possible to realize an object detection device with various characteristics such as temperature characteristics and noise resistance.

Note that in the object detection device having such a configuration, the waveguide 1.
If waveguide 1.2 is formed of a flexible tube, the piping form of waveguide 1.2 can be changed as necessary on-site when installing the device, and changes in the installation location can be easily handled.

Furthermore, by forming the waveguide 1.2 from a material that is chemical-resistant, oil-resistant, etc. in accordance with the environment, it becomes possible to use it in places with poor environments.

<Effects of the Invention> As explained above, according to the object detection device of the present invention using an ultrasonic sensor, ultrasonic waves are propagated directionally through a pair of waveguides without being diffused. This makes it possible to reduce the object sensing range and improve the detection accuracy of minute objects, and also allows the ultrasonic propagation path to be freely set, which means that the installation location can be chosen more freely than before. It is possible to prevent problems such as detecting objects other than objects such as peripheral devices, receiving reflected waves from the objects, and preventing ultrasonic waves from reaching far away.

[Brief explanation of the drawing]

FIG. 1 is a perspective view showing one embodiment of an object detection device according to the present invention, and FIG. 2 is a partial sectional view showing another embodiment. 1.2... Waveguide 3... Transmitter 4... Receiver 5... Voltage application circuit 6... Detection Circuit 7..." Ribbed rubber

Claims (3)

[Claims] (1) A pair of waveguides that can face each other with their distal ends spaced apart, a transmitter that generates ultrasonic waves disposed at the base end of one waveguide, and a transmitter that generates ultrasonic waves at the base end of one waveguide. A receiver is provided at the proximal end and generates an electrical signal by receiving ultrasonic waves.
An object detection device characterized in that the object detection device is configured to detect the presence or absence of an object at the tip separation portion of the waveguide as a change in an electric signal generated from a wave receiver. (2) The object detection device according to claim 1, wherein the waveguide is a flexible tube. (3) An object according to claim 1 or 2, characterized in that a membrane-like vibrating member capable of propagating ultrasonic vibrations is airtightly stretched over the tip surfaces of each of the pair of waveguides. Detection device.